1. Field of the Invention
The present invention relates to a method and apparatus for cleaning loaded engine exhaust filter elements and disposing of the loosened particulate material.
2. Description of the Prior Art
Many methods and devices for cleaning loaded air filters are known. The present invention provides a method and apparatus for cleaning loaded air filters from an engine exhaust stream which combusts the soot and other trapped material without interrupting normal exhaust flow.
Prior methods for cleaning air filters fail to dispose of loosened particulate in a satisfactory manner. Ceramic type filters must undergo exposure to extreme heat in order to burn off the trapped particulate matter. However, this requires expensive filters which are able to withstand the high temperatures. This method limits the types of filters which may be used. This method also requires that the filter be fitted directly to a heater element in order to combust the trapped materials.
Other filters are removed and replaced when the filter becomes loaded. However, replacing filters can add greatly to the operational costs. In addition, the filters are difficult to handle as the soot is hazardous and difficult to contain when the filter is removed. Disposal of the soot requires extremely careful handling.
Methods of providing a reverse blast of air require stopping the main air flow while the reverse blast is being delivered. This interruption of normal flow decreases the efficiency of the engine and requires more complicated control devices.
Although vehicles having air brakes and other types of equipment may come equipped with accumulators to store pressurized air, all devices may not have accumulators. Therefore reverse flow cleaners have required a separate pressure tank to supply the pressurized air for a reverse flow. Such additional containers are typically very large, requiring an additional amount of space.
U.S. Pat. No. 4,218,227 to Frey and assigned to Donaldson Company, Inc., assignee of the present application, shows a Dust Collector. The collector utilizes sixteen pleated filter elements. A reverse blast is utilized to clean the elements, but the pleated filter elements which are being cleaned must be taken off line. This requires a sufficient number of elements to allow some of the elements to be taken off line for cleaning.
U.S. Pat. No. 4,395,269 to Schuler and assigned to Donaldson Company, Inc., assignee of the present application, shows a Compact Dust Filter Assembly. A number of pleated filter elements having a plurality of chambers are cleaned with a reverse pulse jet. The pleated filter elements are angled downwardly to utilize gravity to aid in particle collection.
U.S. Pat. No. 5,123,243 to Baddour shows a Method and Apparatus for Trapping and Incinerating Particulate Matter Found in Diesel Engine Exhaust. Exhaust flow is interrupted and a reverse pulse is directed at the filter while the flow is stopped. Loosened particulate matter is transported to the engine intake whereat the particulate matter is combusted.
It can be seen then, that an improved method and apparatus are needed for cleaning exhaust air filters with a reverse surge of air. It can be appreciated that such a method should not create an excessive backpressure on the engine and that it is preferred that such a method does not interrupt the exhaust flow from the engine. Such a method and apparatus should not require an additional large pressure tank to provide the reverse flow. It can further be appreciated that such a method and apparatus be able to safely retain and dispose of loosened particulate material from the filter. The present invention addresses these and other problems associated with cleaning loaded filters with a reverse blast of air.